Rock Identifier
Orthoceras Fossil (Orthoceras sp. (Extinct genus of nautiloid cephalopod)) — fossil
fossil

Orthoceras Fossil

Orthoceras sp. (Extinct genus of nautiloid cephalopod)

AI-generated identification · may be incorrect

Polished finish, black limestone matrix with white/grey calcified fossils. Hardness: 3-4 (matrix). Features conical shell structures with visible septa (internal chambers).

Hardness
3-4 (matrix)
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Physical properties

Polished finish, black limestone matrix with white/grey calcified fossils. Hardness: 3-4 (matrix). Features conical shell structures with visible septa (internal chambers).

Formation & geological history

Formed during the Ordovician period (approx. 400-485 million years ago) in marine environments. These specimens are most commonly sourced from the Erfoud region of Morocco.

Uses & applications

Informational/educational displays, decorative paperweights, jewelry (pendants/cabochons), and metaphysical collecting.

Geological facts

The name 'Orthoceras' means 'straight horn,' referring to its characteristic long, conical shell. They are ancestors to the modern squid and lived inside these shells while moving through the ocean.

Field identification & locations

Identified by the distinct white conical shapes against a dark grey or black background. Frequently found in large 'death beds' within limestone slabs in North Africa.

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Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone) (Bioclastic limestone, composed chiefly of calcite (CaCO₃)) — sedimentary

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

sedimentary
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Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

sedimentary
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Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

fossil